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We study lens physiology, the physiology of aqueous humor dynamics and regulation of Na,K-ATPase activity. We have been interested in the mechanistic role of Src tyrosine kinase signaling, TRPV1 and TRPV4 ion channels, and connexin hemichannels. Mechanosensitive ion channels seem to be very important. Recently we have become intrigued by piezo1 and TRPM3 channels. Mutation of TRPM3 is associated with early onset cataract in humans.

Astrocytes isolated from the mouse optic nerve head. These star-shaped cells are important for the survival of the neurons that transmit signals from retina to brain.
TRPV4 permits remote control of Na,K-ATPase activity in lens epithelium. TRPV4 channels are activated by swelling of the lens structure. This causes connexin/pannexin hemichannels to open, which releases ATP that stimulates purinergic receptors. This activates Src family tyrosine kinases that act to increase Na,K-ATPase activity.
The bulk of the lens consists of tightly packed fiber cells. The ion content of the entire structure is regulated by Na,K-ATPase in the monolayer of epithelial cells that covers the anterior surface. Na,K-ATPase is a pump that uses energy from ATP hydrolysis to transport sodium ions outwards and potassium ions inwards.
Aqueous humor is formed continuously by the ciliary body. It flows through the anterior part of the eye and leaves the eye at the 'angle' where iris meets the cornea. Because of aqueous humor secretion the inside of the eye is pressurized, rather like an inflated ball.
Aqueous humor formation by the ciliary body.
“My genome is not a straitjacket but a soft sweater to fill and shape, to snuggle up and stretch out in. So who am I? I am what I do with this beautiful information that has flowed through millions of years through billions of organisms and has, now, finally been entrusted to me.” Quote by Lone Frank, from “My Beautiful Genome” (2011) Oneworld Press.
Most lens cells have little or no Na,K-ATPase activity. Ion and water homeostasis of the entire structure is maintained by a small number of cells at the periphery of an epithelial monolayer at the anterior surface.
“A single living cell is much more beautiful and improbable than the solar system. So far scientists have not explained away the wonder of the cell nor stripped it of its mystery. On the contrary, in the words of Alice in Wonderland, the cell gets ‘curiouser and curiouser’ the more we learn about it.” Honor Fell (1900 – 1986), former Director of Strangeways Research Laboratory, Cambridge UK. (Image: Wellcome Library)